As a warning, this is going to go beyond the limits of the inital question, but I think it's all still in bounds & relavant to the question.
In my opinion you're best served by having your carry guns be of the same platform. For instance, if you're carrying a Glock then stick to that type, but if you need to you can have a 17 for winter clothing, a 19 for "most of the time" & a 26 if you need something tiny and/or as a BUG.
I'm not just a big fan of using the same platform, but keeping everything on or for that platform the same or as similar as possible as well. Same sights, same holster, same mag carriers, etc...
The less you have to think about the better off you'll be. As an example if I'm doing a Type 3 malfxn clearance I found that I'm nearly a full second faster if I stand in one place vs. moving. Now obviously moving while my gun is down is more advantageous than getting back into the fight a second faster but the point is that my brain is having to process movement & the clearance drill which slows things down & I've been walking for 30 or so years & have thousands of Type-3 practice drills under my belt.
Same thing goes for your brain having to decide which gun you're using. You may not feel slower but I'll bet if you commit to using one platform & put yourself on a shot timer you'll see an improvement in your speed & if you're honest with yourself you'll see an improvement in your shooting as well.
I'm not all that familiar with the whole "The average defensive shooting is within X yards, involves Y shots & is over in Z seconds" stats, but If the entire scenario takes 10 seconds start to finish & you're well trained so you're only 1/2 a second slower than you could be you're still wasting 5% of the time you have. If you consider that, as the defender, you are starting at a disadvantage then the 5% you've comped to your attacker could be enough to keep you from catching up to your OODA loop.
As an example, which person would you rather be:
A- I'm being attacked, MOVE! Now am I carrying my 1911 with the Heinie Straight-8 sights, in my Sparks VM-II behind my hip or is it my S&W airweight with the stock sights in the front pocket, or my Kahr with the Trijicon front & stock rear in the Comp-Tac AIWB rig or my G-26 with the Big Dots in the ankle holster or...
B- I'm being attacked, MOVE! Grab the gun that's where it always is & get to doing God's work.
If you're person A, even though you know you chose the 1911 & none of the other options that day your brain will still have to burn time thinking about what to do.
I will admit that person B is a bit ideal, but the point is to have as much similarity as possible. For instance, if you carry a G-19 in a SmartCarry for your Sunday go to meetin' & workout wear & the same gun in an AIWB holster for your everyday clothing there will be less thinking required because your gun will be in a very similar orientation it's just a matter of do I grab above the belt or below.
SoutNarc has a great article on Shivworks.com titled "A Systems Approach to Building a Profile" that covers a lot of this on integrating the h2h/knife/gun platforms.
Carrying a gun is not an easy task & the responsibility you take on demands that you're proficient so train up, practice & be ready to use it while you hope you never have to.